The present invention concerns a fastening arrangement between a profile bar and the adjustment spindles thereof at a discharge opening of a head box in a paper machine. The profile of the profile bar is adjusted by means of the adjustment spindles, this profile determining transverse profile of the discharge opening of the head box.
A profile bar is used at an upper lip of a head box, with the profile of the discharge opening being adjusted by means of this profile bar, as is known in the prior art. For this purpose, several dozen adjustment spindles have been attached to the profile bar in the transverse direction of the headbox. The profile bar can be deflected by means of these spindles, for the purpose of adjusting the profile of the discharge opening.
High precision is required for the adjustment of the profile of the discharge opening. This is why great requirements are imposed on the fastening of the profile bar and the adjustment spindles. More and more precise adjustments of the transverse profile of grammage are needed with increasing running speeds of paper machines and with more and more strict requirements being imposed on the properties of paper. This imposes constantly increasing requirements on the means of adjustment of the profile bar.
With respect to the prior art related to the present invention, reference is made to Finnish Pat. No. 41,342 of the assignee, in which a prior art fastening of the profile bar is described in which adjusting movement of the adjustment spindles is transferred in the axial direction of the adjustment spindles eccentrically. This is why bending moments are generated in the profile bar, causing uncontrolled behavior, e.g. jerks, of the profile bar, so that the profile of the profile bar does not follow the adjusting movements of the adjustment spindles in a linear fashion.
Furthermore, certain fastening arrangements between the profile bar and the adjustment spindles are known in the prior art, in which the fastening point is situated on the axial centre line of the adjustment spindles. However, the significance of this central looation was not realized in the prior art, because the earlier requirements imposed on the adjustment of the profile bar were not equally as great as they are today. With respect to these central fastenings, reference is made by way of example, to Finnish Pat. No. 34,054, and to Finnish Patent Applications Nos. 772,145 and 810,671.